Heat dissipating substrate and method of manufacturing the same

ABSTRACT

Disclosed herein are a heat dissipating substrate and a method of manufacturing the same. The heat dissipating substrate includes: a substrate that is formed of a metal material, wherein at least one via hole is formed in the substrate; an insulating layer formed on a surface of the substrate; a coating layer that is formed on an inner wall surface of the via hole and is formed of a conductive or non-conductive material; a plurality of metal patterns that are formed on the insulating layer and are electrically separated from one another; a metal layer that is extended from the metal patterns to be formed on the coating layer formed on the inner wall surface of the via hole; and a filling material that is formed of a non-conductive material and is filled between the metal layers in the via hole.

CROSS REFERENCE(S) TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. Section 119 ofKorean Patent Application Serial No. 10-2011-0139245, entitled “HeatDissipating Substrate and Method of Manufacturing the Same” filed onDec. 21, 2011, which is hereby incorporated by reference in its entiretyinto this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a heat dissipating substrate and amethod of manufacturing the same, and more particularly, to a heatdissipating substrate formed of a metal, wherein a surface of the heatdissipating substrate is anodized, and an inner wall surface of a via ofthe heat dissipating substrate is plugged using a conductive ornon-conductive material, and a method of manufacturing the heatdissipating substrate.

2. Description of the Related Art

In general, various light emitting units such as a light emitting diode(LED) are mounted on a substrate, and when they are driven as alight-emitting body, heat is generated due to light emission, and theheat needs to be effectively dissipated to increase the lifespan andefficiency of the light emitting units.

In particular a LED has low power consumption and high luminance, andthus is widely used as a light source for homes and industrial purposes.

Recently, a LED is used as a light source of illuminating apparatusesand backlights for liquid crystal displays (LCD). The LED is supplied ina package which is easily mounted in various devices such asilluminating apparatuses.

A LED package has a structure in which the LED package is mounted on asubstrate and a LED is encapsulated by using a molding material. Here,not only are the functions of the LED package of protecting the LED andproviding a connection to a light emitting device important, but heatdissipation performance of the LED package for dissipating heat from theLED is also an important evaluation standard for evaluating LEDpackages.

Since a contact surface of a LED with a substrate is the largest, andheat may preferably be dissipated through the substrate, and variousheat dissipation structures for dissipating heat through a substrate arebeing developed.

The most effective way of dissipating heat of a light emitting unit isto include a metal substrate so that heat generated in the lightemitting unit is dissipated through the metal substrate to the outside,and accordingly, various researches are being conducted into a heatdissipating substrate which may increase performance and lifetime of aLED, by simplifying a structure of the heat dissipating substrate andimproving heat dissipation performance thereof.

RELATED ART DOCUMENT Patent Document

(Patent Document 1) Korean Patent Laid-Open Publication No. 2010-016737

SUMMARY OF THE INVENTION

An object of the present invention is to provide a heat dissipatingsubstrate in which an inner wall surface of a via formed in a metalsubstrate is plugged using a conductive or non-conductive material so asto fill an inner portion of the via using the non-conductive material,thereby reducing a size of the via hole, and a method of manufacturingthe same.

According to an exemplary embodiment of the present invention, there isprovided a heat dissipating substrate, comprising: a substrate that isformed of a metal material, wherein at least one via hole is formed inthe substrate; an insulating layer formed on a surface of the substrate;a coating layer that is formed on an inner wall surface of the via holeand is formed of a conductive or non-conductive material; a plurality ofmetal patterns that are formed on the insulating layer and areelectrically separated from one another; a metal layer that is extendedfrom the metal patterns to be formed on the coating layer formed on theinner wall surface of the via hole; and a filling material that isformed of a non-conductive material and is filed between the metallayers in the via hole.

The substrate may be formed of a metal having an excellent thermalconductivity, and be formed of aluminum (Al).

The insulating layer formed on the surface of the substrate may beformed of an oxide coating layer (Al₂O₃) by anodizing.

The via hole may be formed by using a mechanical method such as drillingor punching or a chemical method such as etching.

According to another exemplary embodiment of the present invention,there is provided a method of manufacturing a heat dissipatingsubstrate, the method comprising: preparing a metal substrate andforming at least one via hole that passes through the metal substrate;forming an insulating layer on a surface of the metal substrateincluding the via hole; forming a coating layer using a non-conductivematerial on an inner wall surface of the via hole, on which theinsulating layer is formed; forming a metal layer on the coating layerformed on the inner wall surface of the via hole and the insulatinglayer formed on the surface of the metal substrate; forming a pluralityof metal patterns by patterning the metal layer formed on the insulatinglayer formed on the surface of the metal substrate; and injecting afilling material formed of a non-conductive material between coatinglayers formed on the inner wall surface of the via hole.

In the forming of the insulating layer on a surface of the metalsubstrate, the insulating layer may be formed of an oxide coating layerby anodizing.

The forming of the coating layer on an inner wall surface of the viahole may include: filling a non-conductive material in the via holethrough a plugging process; and forming a through hole in thenon-conductive material filled in the via hole.

The non-conductive material filled in the via hole may be epoxy orpolymer, and the through hole may be formed by drilling or laserprocessing.

According to another exemplary embodiment of the present invention,there is provided a method of manufacturing a heat dissipatingsubstrate, the method comprising: preparing a metal substrate andforming at least one via hole that passes through the metal substrate;forming an insulating layer on a surface of the metal substrateincluding the via hole; forming a coating layer formed of a conductivematerial on an inner wall surface of the via hole, on which theinsulating layer is formed; forming a metal layer on the coating layerformed on the inner wall surface of the via hole and the insulatinglayer formed on the surface of the metal substrate; forming a pluralityof metal patterns by patterning the metal layer formed on the insulatinglayer formed on the surface of the metal substrate; and injecting afilling material formed of a non-conductive material between the coatinglayers formed on the inner wall surface of the via hole.

The forming of the coating layer on an inner wall surface of the viahole may include: fill plating an inner portion of the via hole using aconductive material through a plating process; and forming a throughhole in the fill-plated conductive material formed in the via hole.

In the forming of the coating layer on an inner wall surface of the viahole, the coating layer may be formed as a seed layer only on the innerwall surface of the via hole by using a conductive material and aplating process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a heat dissipatingsubstrate according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a heat dissipating substrateaccording to an embodiment of the present invention, on which a lightemitting unit is mounted;

FIGS. 3A through 3H are schematic views illustrating a method ofmanufacturing a heat dissipating substrate according to an embodiment ofthe present invention; and

FIGS. 4A through 4G are schematic views illustrating a method ofmanufacturing a heat dissipating substrate according to anotherembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the technical configuration of the light emitting diodepackage according to the present invention and the effects thereof willbe clearly understood from the detailed description below with referenceto the accompanying drawings in which exemplary embodiments of thepresent invention are shown.

First, FIG. 1 is a cross-sectional view illustrating a heat dissipatingsubstrate 100 according to an embodiment of the present invention.

As illustrated in FIG. 1, the heat dissipating substrate 100 may includea substrate 110 formed of a metal material, an insulating layer 120formed on a surface of the substrate 110, a coating layer 130 formed onan inner wall surface of a via hole 111 formed in the substrate 110, ametal pattern 150 formed on the insulating layer 120 formed on thesurface of the substrate 110, a metal layer 140 formed on the coatinglayer 130, and a filling material 160 filled in inner portions of themetal layer 140.

The substrate 110 may be formed of a metal such as an aluminum (Al)which is a representative metal having excellent thermal conductivity,and at least one via hole 111 may be formed on the substrate 110.

The via hole 111 may be formed by CNC drilling or etching. Also, the viahole 111 may be used as an electrical connection portion thatelectrically connects metal patterns 150 formed on upper and lowersurfaces of the substrate 110 which will be described below.

The insulating layer 120 may be formed on the entire surface of thesubstrate 110 including the inner wall surface of the via hole 111. Theinsulating layer 120 may be formed on the substrate 110, which is formedof aluminum, using an oxide coating layer (Al₂O₃) by anodizing. Theanodizing may be performed by using an organic acid, a sulfuric acid, ora mixture thereof.

Aluminum used to form the substrate 110 is a metal which is easilyobtainable at relatively low price, and has excellent thermalconductivity, and an oxide coating layer formed on a surface of thesubstrate 110 may also be formed using a thin insulator that has arelatively high thermal conductivity of about 10 to 30 W/mK byanodizing, thereby providing low thermal resistance.

Accordingly, compared to copper or ceramics which is used to form asubstrate according to the related art, not only has the substrate 110formed of aluminum excellent heat dissipation performance but also thesubstrate 110 may be anodized relatively easily, and thus the costs andtime for processing may be reduced.

The coating layer 130 is formed on the inner wall surface of the viahole 111, and the coating layer 130 may be formed of a conductivematerial such as a metal or a non-conductive material such as epoxy orpolymer.

When the coating layer 130 is formed of a conductive material, thecoating layer 130 may be formed by plating, and when the coating layer130 is formed of a non-conductive material, the via hole 111 may befilled with a non-conductive material so as to completely fill the viahole 111, and then a through hole is formed by drilling or laserprocessing so that the coating layer 130 is formed only on the innerwall surface of the via hole 111.

Also, the metal patterns 150 are electrically separated from adjacentmetal patterns on the insulating layer 120, and a portion on the metalpatterns 150 where a light emitting unit such as a LED is to be mountedmay be formed as an electrode portion. The metal patterns 150 may beextended inwardly into the via hole 111 and be formed as the metal layer140 on the coating layer 130. The metal patterns 150 may perform thefunction as an electrode and the function of heat dissipation at thesame time.

The metal patterns 150 may be formed on the insulating layer 120 asillustrated in FIG. 1, or alternatively, a portion of the insulatinglayer 120 may be removed and the metal patterns 150 may be formed on anexposed portion of an upper surface of the substrate 110. In this case,a lower surface of the metal pattern 150 directly contacts the uppersurface of the substrate 110, and a LED is mounted on an upper surfaceof the metal pattern 150, thereby further enhancing the effects of heatdissipation of the LED.

As described above, the insulating layer 120, the coating layer 130, andthe metal layer 140 extended from the metal patterns 150 may besequentially formed in the via hole ill, and a through hole is formedbetween portions of the metal layer 140 so as to fill a filling material160 in the through hole. The filling material 160 may be epoxy orpolymer formed of a non-conductive material, and the metal layer 140formed on inner portions of the via hole 111 is shorted by the fillingmaterial 160 to thereby prevent a short circuit between the metalpatterns 150.

Also, as described in the objective of the present invention, as theinsulating layer 120, the coating layer 130, and the metal layer 140 aresequentially formed in the via hole 111 which is formed to have arelatively large size by drilling or punching due to characteristics ofthe metal substrate 110, a diameter of the via hole 111 may be reduced,and the filling material 160 may be injected into the reduced via hole111.

Consequently, when heat is dissipated through the substrate 110 which isformed of a metal material, due to the characteristics of a metalsubstrate, the via hole 111 is constricted or expanded by the heat, andhere, by reducing the diameter of the via hole 111 by using the coatinglayer 130 formed on the inner wall surface of the via hole 111,variation in the diameter of the via hole 111 due to thermal deformationof the substrate 110 may be minimized.

Various types of light emitting units may be mounted on a heatdissipating substrate having the above-described structure according tothe present invention, and a structure in which a LED is mounted as alight emitting unit will be briefly described as an example below.

FIG. 2 is a cross-sectional view of a heat dissipating substrateaccording to an embodiment of the present invention, on which a lightemitting unit is mounted.

At least one via hole 111 is formed so that a light emitting unit 200,for example, a LED (hereinafter referred to as a LED chip 200) may bemounted on a substrate 110 which is formed of a metal material and onupper and lower surfaces of which metal patterns 150 are formed.

The LED chip 200 is a LED chip having a vertical electrode structure,and one electrode (not shown) formed on the LED chip 200 is directlyconnected to the metal patterns 150, and the other electrode (not shown)may be electrically connected to the metal patterns 150, on which theLED chip 200 is not mounted, via a wire 210. Here, the metal patterns150 connected to the LED chip 200 via the wire 210 may be extended up tothe lower surface of the metal substrate 110 via the metal layer 140that is extended to an inner portion of the via hole 111.

Also, a molding unit 220 that covers the LED chip 200 and the wire 210may be formed on the substrate 110. The molding unit 220 may be formedto a desired form by using a silicon resin, an epoxy resin, or an epoxymolding compound (EMC) or the like and by using a method using aninjection molding method, a transfer molding method, or a pin gatemolding method.

Hereinafter, a method of manufacturing the heat dissipating substratehaving the above-described structure will be described.

FIGS. 3A through 3H are schematic views illustrating a method ofmanufacturing a heat dissipating substrate according to an embodiment ofthe present invention.

As illustrated in the drawings, first, a metal substrate 110 is preparedas illustrated in FIG. 3A. The metal substrate 110 may be preferably analuminum substrate that is gone through a washing operation in whichpollutants such as organic materials on a surface thereof are washedoff.

The metal substrate 110 may typically have a square shape, or othervarious forms such as a rectangular or a circular shape according to aprocessed aluminum substrate. In addition, a thickness of the metalsubstrate 110 may preferably be about 0.1 mm or greater in considerationof process reliability.

Next, as illustrated in FIG. 3B, at least one via hole 111 that passesthrough the metal substrate 110 is formed. The via hole 111 may beformed by drilling, punching, or etching.

Also, an insulating layer 120 may be formed on a surface of the metalsubstrate 110 including the via hole 111 by anodizing.

Next, a coating layer 130 formed of a non-conductive material may beformed on an inner wall surface of the via hole 111, on which theinsulating layer 120 is formed. The coating layer 130 may be formed byfilling a resin material such as epoxy or polymer which is anon-conductive material, in the via hole 111 on which the insulatinglayer 120 is formed, and by forming a through hole 131 that passesthrough a center portion of the non-conductive material filled in thevia hole 111, as illustrated in FIG. 3E. Here, the through hole 131 maybe formed by drilling or laser processing.

Next, as illustrated in FIG. 3F, a metal layer 140 may be formed on theinsulating layer 120 of the metal substrate 110 that includes thecoating layer 130 formed on the inner wall surface of the via hole 111.The metal layer 140 may be formed by using a method such aselectroplating, electroless plating, or metal deposition.

While the metal layer 140 is formed, an inner portion of the via hole111 may be completely filled with the metal layer 140 or the metal layer140 may be formed as a thin layer on the coating layer 130 on the innerwall surface of the via hole 111. When the metal layer 140 is completelyfilled in the inner portion of the via hole 111, a previous process,that is, a process (not shown) of forming a through hole one more timeso that the metal layer 140 filled in the via hole 111 is shorted, likea process of forming the through hole 131 in the non-conductive materialfilled in the via hole 111 may be performed.

As described above, by further forming the coating layer 130 and themetal layer 140 on the inner wall surface of the via hole 111, a size ofthe via hole 111 may be reduced, and variation in the size of the viahole 111 due to constriction or expansion of the metal substrate 110 dueto thermal deformation may be minimized.

Next, as illustrated in FIG. 3G, the filling material 160 is injectedinto the inner portion of the metal layer 140 in the via hole 111 so asto completely fill the inner portion of the via hole 111. Here, thefilling material 160 may be a non-conductive material such as epoxy orpolymer.

Finally, as illustrated in FIG. 3H, the metal layer 140 formed on asurface of the insulating layer 120 may be patterned to form a pluralityof metal patterns 150 that are formed on the insulating layer 120 formedon upper and lower surfaces of the metal substrate 110 and areelectrically separated.

FIGS. 4A through 4G are schematic views illustrating a method ofmanufacturing a heat dissipating substrate according to anotherembodiment of the present invention.

As illustrated in the drawings, first, a metal substrate 110 is preparedas illustrated in FIG. 4A. The metal substrate 110 may be preferably analuminum substrate that is gone through a washing operation in whichpollutants such as organic materials on a surface thereof are washedoff.

The metal substrate 110 may typically have a square shape, or othervarious forms such as a rectangular or circular shape according to aprocessed aluminum substrate. In addition, a thickness of the metalsubstrate 110 may preferably be about 0.1 mm or greater in considerationof process reliability.

Next, as illustrated in FIG. 4B, at least one via hole 111 that passesthrough the metal substrate 110 is formed. The via hole 111 may beformed by drilling, punching, or etching.

Also, as illustrated in FIG. 4C, an insulating layer 120 may be formedon a surface of the metal substrate 110 including the via hole 111 byanodizing.

Next, as illustrated in FIG. 4D, a coating layer 130 formed of aconductive material may be formed on an inner wall surface of the viahole 111 on which the insulating layer 120 is formed. The coating layer130 may be formed in the via hole 111 on which the insulating layer 120by using a plating process, and in detail, as a seed layer on theinsulating layer 120 on the inner wall surface of the via hole 111 byelectroplating or electroless plating.

Also, the coating layer 130 may be formed only on the inner wall surfaceof the via hole 111 by fill-plating an inner portion of the via hole 111with a conductive material by plating, and then by forming a throughhole 131 in the conductive material filled in the via hole 111. Thethrough hole 131 may be formed by drilling or etching.

Next, as illustrated in FIG. 4E, a metal layer 140 may be formed on theinsulating layer 120 of the metal substrate 110 that includes thecoating layer 130 formed on the inner wall surface of the via hole 111.The metal layer 140 may be formed by electroplating, electrolessplating, or metal deposition.

Here, while the metal layer 140 is formed, the inner portion of the viahole 111 may be completely filled with the metal layer 140 or the metallayer 140 may be formed as a thin layer on the coating layer 130 on theinner wall surface of the via hole 111. When the metal layer 140 iscompletely filled in the inner portion of the via hole 111, a previousprocess, that is, a process of forming a through hole one more time sothat the metal layer 140 filled in the via hole 111 is shorted, like aprocess of forming the through hole 131 in the non-conductive materialfilled in the via hole 111 may be performed.

As described above, by further forming the coating layer 130 and themetal layer 140 on the inner wall surface of the via hole 111, a size ofthe via hole 111 may be reduced, and variation in the size of the viahole 111 due to constriction or expansion of the metal substrate 110 dueto thermal deformation may be minimized.

Next, as illustrated in FIG. 4F, the filling material 160 is injectedinto the inner portion of the metal layer 140 in the via hole 111 so asto completely fill the inner portion of the via hole 111. Here, afilling material 160 may be a non-conductive material such as epoxy orpolymer.

Finally, as illustrated in FIG. 4G, the metal layer 140 formed on asurface of the insulating layer 120 may be patterned to form a pluralityof metal patterns 150 that are formed on the insulating layer 120 onupper and lower surfaces of the metal substrate 110 and are electricallyseparated.

As described above, according to the heat dissipating substrate and themethod of manufacturing the heat dissipating substrate according to theembodiments of the present invention, heat generated in a light emittingmember mounted on the upper surface of the metal substrate may beefficiently dissipated through the metal substrate.

In addition, a coating layer formed of a conductive or non-conductivematerial is formed on an inner wall surface of a via hole, and spaceinside the coating layer is filled, thereby reducing a size of a via.Accordingly, variation in a diameter of the via hole due to thermaldeformation of a metal substrate according to contraction or expansionof a metal material may be minimized.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims. Accordingly, suchmodifications, additions and substitutions should also be understood tofall within the scope of the present invention.

What is claimed is:
 1. A heat dissipating substrate, comprising: asubstrate that is formed of a metal material, wherein at least one viahole is formed in the substrate; an insulating layer formed on a surfaceof the substrate; a coating layer that is formed on an inner wallsurface of the via hole and is formed of a conductive or non-conductivematerial; a plurality of metal patterns that are formed on theinsulating layer and are electrically separated from one another; ametal layer that is extended from the metal patterns to be formed on thecoating layer formed on the inner wall surface of the via hole; and afilling material that is formed of a non-conductive material and isfilled between the metal layers in the via hole.
 2. The heat dissipatingsubstrate according to claim 1, wherein the substrate is formed of ametal having an excellent thermal conductivity and is formed of aluminum(Al).
 3. The heat dissipating substrate according to claim 1, whereinthe insulating layer formed on the surface of the substrate is formed ofan oxide coating layer (Al₂O₃) by anodizing.
 4. The heat dissipatingsubstrate according to claim 1, wherein the via hole is formed by usinga mechanical method such as drilling or punching or a chemical methodsuch as etching.
 5. The heat dissipating substrate according to claim 1,wherein the metal patterns are formed on portions of an upper surface ofthe substrate that are exposed by removing a portion of the insulatinglayer.
 6. The heat dissipating substrate according to claim 1, whereinthe filling material is formed of a non-conductive material such asepoxy or polymer.
 7. A method of manufacturing a heat dissipatingsubstrate, the method comprising: preparing a metal substrate andforming at least one via hole that passes through the metal substrate;forming an insulating layer on a surface of the metal substrateincluding the via hole; forming a coating layer using a non-conductivematerial on an inner wall surface of the via hole, on which theinsulating layer is formed; forming a metal layer on the coating layerformed on the inner wall surface of the via hole and the insulatinglayer formed on the surface of the metal substrate; forming a pluralityof metal patterns by patterning the metal layer formed on the insulatinglayer formed on the surface of the metal substrate; and injecting afilling material formed of a non-conductive material between coatinglayers formed on the inner wall surface of the via hole.
 8. The methodaccording to claim 7, wherein in the forming of the insulating layer ona surface of the metal substrate, the insulating layer is formed of anoxide coating layer by anodizing.
 9. The method according to claim 7,wherein the forming of the coating layer on an inner wall surface of thevia hole includes: filling a non-conductive material in the via holethrough a plugging process; and forming a through hole in thenon-conductive material filled in the via hole.
 10. The method accordingto claim 1, wherein the non-conductive material filled in the via holeis epoxy or polymer, and the through hole is formed by drilling or laserprocessing.
 11. A method of manufacturing a heat dissipating substrate,the method comprising: preparing a metal substrate and forming at leastone via hole that passes through the metal substrate; forming aninsulating layer on a surface of the metal substrate including the viahole; forming a coating layer formed of a conductive material on aninner wall surface of the via hole, on which the insulating layer isformed; forming a metal layer on the coating layer formed on the innerwall surface of the via hole and the insulating layer formed on thesurface of the metal substrate; forming a plurality of metal patterns bypatterning the metal layer formed on the insulating layer formed on thesurface of the metal substrate; and injecting a filling material formedof a non-conductive material between the coating layers formed on theinner wall surface of the via hole.
 12. The method according to claim11, wherein the forming of the coating layer on an inner wall surface ofthe via hole includes: fill plating an inner portion of the via holeusing a conductive material through a plating process; and forming athrough hole in the fill-plated conductive material formed in the viahole.
 13. The method according to claim 11, wherein in the forming ofthe coating layer on an inner wall surface of the via hole, theconductive material is formed, as a seed layer, only on the inner wallsurface of the via hole through a plating process.